Do you run the same fuel rod winter and summer? I have mine all tuned up for summer riding with a 3-2m and wondering if I need to change anything for winter.
Setting up the 300 XC for snow
- Thread starter GlennRMK
- Start date
Do you run the same fuel rod winter and summer? I have mine all tuned up for summer riding with a 3-2m and wondering if I need to change anything for winter.
M
mxracer299
Well-known member
I have 2 dirt and snow seasons on my modded 300. Here's what I have settled on for a setup. Porting and head cut, 42 thousandths squish, any less and you will need race fuel and lose over rev. Scalavini pipe, it works waaay better than any other pipe, I have tried pretty much every one. Boyseen rad valve and pro series reeds. Modified exhaust manifold, weld up the top outside so you can grind out the inside enough to match ports. 38mm carb, 40mm works but you lose too much bottom IMO, every brand has its quirks... lectron, kehin, smart carb. SX ignition makes a noticeable difference, comes on quicker and revs faster, if it doesn't add hp the seat of the pants feel sure doesnt agree. Another thing to not over look is your spark plug, the br7 is too hot with the sx ignition on a mod motor, I've had really good luck with the br8eix plug, it's easier to get my jetting consistent and works well in dirt too, I don't like the br7 in high rev environments. Red PV spring. This setup has outrun pretty much every 450 I've run it against! As far as the 330 kit vs 300, the 330 pulls noticeably harDer off the bottom and the 300 pulls harder on top. I don't know which is better but I wouldn't go 330 unless I burnt a cylinder, the other downfall of the 330 is it vibrates a lot. After riding a lot of 300s in every configuration possible it's pretty apparent that if you do a few of the mods it doesn't do much. An engine is an air pump with 3 stages, intake, combustion and exhaust, if you don't increase the amount of air in all three places you just aren't going to gain much efficiency. Good luck!
Ooh and one more thing, run an EGT Guage! It will make life a lot easier, I've ran stock carbs with JD reccomendations, lectron and smart carb, none of their reccomended setups were close, some of them were off far enough to burn up a motor in the first full pull. Figure on spending the first few rides getting a baseline setting, carbs take work, especially on a modded bike, every bike and every environment has a different setup.
Ooh and one more thing, run an EGT Guage! It will make life a lot easier, I've ran stock carbs with JD reccomendations, lectron and smart carb, none of their reccomended setups were close, some of them were off far enough to burn up a motor in the first full pull. Figure on spending the first few rides getting a baseline setting, carbs take work, especially on a modded bike, every bike and every environment has a different setup.
Egt= happy life.. Most people will never know how good their engine could run without it... I was in that group...
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Thanks for the input
I was thinking about running the BR8 or BR9 for all the high RPM
I haven't ordered anything yet, but getting excited to see how it works this season
I hope my 2016 LT works well with it
I was thinking about running the BR8 or BR9 for all the high RPM
I haven't ordered anything yet, but getting excited to see how it works this season
I hope my 2016 LT works well with it
M
mxracer299
Well-known member
There's 4 300s in my group, I have a sxlt and every other one is a LT. It will turn a LT just fine. On hardpack my won't hook up until 4th gear, it's amazing that a 300 will struggle for traction with a lt, they hit hard! My girlfriends bike is a 300 with sx ignition, PC pipe and stock carb with a LT, it lacks a little power but it works surprisingly well! If you cut the head, PC pipe and 38mm carb you'll be right with 450s pretty much all the time.
I run pretty much what everyone else has said. Gore head, 38mm carb, I run the FMF fatty, carb warmer, red spring 1 turn in. The SX CDI is designed to run with the 250SX crank and 300 conversion which is lighter than the stock 300XC crank. The factory team KTM techs say a xc will run better on the XC box and I'd have to agree. But they do rip and easy to maintain! I have a lectron on order and it should make it more consistant.
M
mxracer299
Well-known member
I started with a 250 xc which supposedly has the same bottom end as the 250 sx. Maybe it works better because of that. I know mine has a different crank, it spins up faster and vibrates less than any 300 I've been on. I've rode all of 40-50 300s over the years.
I am back to a kehin on mine for dirt, took all of 30 minutes to make it run right with the JD needle, I couldn't ever get the smart carb to run lean enough on bottom without getting too lean on top. Mileage is king on dirt, most of our rides are 70-80 miles and the extra fuel is needed for my chainsaw, it goes everywhere with me. I have mine setup borderline lean at 3500' and haven't had any issues riding over 10,000ft, the stock.carbs actually work pretty damn good.
I am back to a kehin on mine for dirt, took all of 30 minutes to make it run right with the JD needle, I couldn't ever get the smart carb to run lean enough on bottom without getting too lean on top. Mileage is king on dirt, most of our rides are 70-80 miles and the extra fuel is needed for my chainsaw, it goes everywhere with me. I have mine setup borderline lean at 3500' and haven't had any issues riding over 10,000ft, the stock.carbs actually work pretty damn good.
Thanks for the info guys.
So the verdict is skip the SX CDI?
I was thinking I would do a top end in it (unknown hours on it) and have slavens cut the head while its off.
I was leaning towards the Pro Circuit pipe. Worth the money?
So the verdict is skip the SX CDI?
I was thinking I would do a top end in it (unknown hours on it) and have slavens cut the head while its off.
I was leaning towards the Pro Circuit pipe. Worth the money?
I've found the stock carb works great one minute but as soon as it changes in temp or humidity even snow buildup on the intake the motor loses its edge and flattens out, its more noticeable with 50hp than with 150 on a sled... Im hoping the Lectron will make it work more consistent. For the dirt I have no complaints with the keihin JD has it dialled for sure.
This is my 2 cents. I would send the head and cylinder off to get ported by Eric Gore mo betta it will make a much bigger difference than just the head I've done both. As far as the SX ECU I find that it gives you a greater RPM range and a better seat-of-the-pants feel but it could match my porting better.
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What about engine shrouds or covers? Recommendations for the 300?
Any other recommendations?
Make sure if you go with a metered carb with heat.. that you have a switch for the carb heat to shut off... I find turning it on when needed works way better than depending on the stat... when the meter carbs get to hot it affects how they run... at least that is my experience. It will affect the idle on the low end.
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The 07 should be a better porting/power combo for snowbiking..... they normally have more of a hit..
Personally I would not want the 5 speed W tranny for snow. I rode an 09 300 XC-W for a while in the dirt and did not like the gappy tranny at all.
I personally would rather have the 5 speed SX tranny over my 6 speed XC tranny in mine but they haven't offered that since 09.
Jetting for 6-9k with the Keihin?
I run a 38 pilot, NECJ needle in the 2nd clip and 152 main in the summer.
I was thinking 40 or 42 pilot, move the clip up a notch, and 168 main for snow?
I run a 38 pilot, NECJ needle in the 2nd clip and 152 main in the summer.
I was thinking 40 or 42 pilot, move the clip up a notch, and 168 main for snow?
Was thinking of getting an SX CDI but which one for my 2011?
One from a 2012 250 SX?
Or the 300 SX CDI from the 300 kit for a 250?
Anyone have a part number?
One from a 2012 250 SX?
Or the 300 SX CDI from the 300 kit for a 250?
Anyone have a part number?
I'm running the Lectron carb with avid heater,S3 high compression head and SX cdi, EGT sensor for piece of mind,K&N filter and snowcharger and threw a 100 watt stator in it.
